Synthesis and characterization of diplatinum complexes containing bridging μ-η2-H-SiHAr ligands.: X-ray crystal structure determination of {(Ph3P)Pt[μ-η2-H-SiHAr]}2 (Ar=2,4,6-(CF3)3C6H2, C6Ph5)

Dinuclear Pt-Si complexes, [(Ph3P)Pt(mu-eta (2)-H-SiHAr)](2) (Ar = 2-isopropyl-6-methylphenyl (IMP), 2,4,6-trimethoxyphenyl (TMP), 2,4,6-trimethylphenyl (Mes), pentaphenylphenyl (PPP), 2,4,6-tris(trifluoromethyl)phenyl (R-F)) have been synthesized fr;om the reaction of ArSiH3 with (Ph3P)(2)Pt(eta (2)-C2H4). These complexes were characterized by multinuclear NMR and IR spectroscopy and X-ray crystallography (PPP and RF systems). The dinuclear complexes contain a 3c-2e nonclassical interaction for Pt . . .H . . . Si, which is supported by spectroscopic and crystallographic data. Both cis and trans isomers are formed when Ar = IMP, TMP, Mes, and these complexes are fluxional on the NMR time scale. Only the trans isomer is generated with Ar = PPP, R-F. These complexes exhibit an unusual low-field H-1 NMR resonance for the terminal Si-H and an upfield shift for the bridging-hydride. X-ray crystallographic analysis of the PPP and R-F systems(also previous results for IMP) reveal two different Si-Pt distances, with the longer distance corresponding to the Pt . . .H . . . Si interaction.